1. Field of Invention
This invention relates to dental model bases and methods of forming dental models.
2. Related Art
A successful repair of damaged teeth either by bridge inlays, replacement by crowns, or other common dental prostheses requires accurate alignment and visual uniformity of the repaired tooth with the patient's other teeth. Typically a model is made of the patient's teeth and the prosthesis is fitted to the model and adjusted to achieve proper alignment and visual uniformity.
The model is typically formed by having the patient bite into a pliant casting material that cures to create a mold cavity having a negative impression of the patient's teeth and gums. The mold can be of all or any portion of the patient's gum line. A castable material is then poured into the negative impression to create a stone replica of dental model of the patient's teeth and gums.
To facilitate prosthesis development, the replica of the damaged tooth or teeth is severed from the remainder of the dental model. Severability is achieved by positioning the tapered end of the dowel pin in an aperture formed in the dental model base that corresponds to the damaged tooth or teeth. Typically, the aperture is formed as part of the dental model base during manufacture or is formed in a cast stone base by allowing the stone to cure around a pin. The knurled end of a tapered dowel pin is placed in the stone material in the negative impression in correspondence with the damaged tooth or teeth. To prevent bonding of the damaged tooth model with the dental model base, wax may be placed between the dental model base and the dental model.
Once the dental model has cured, a saw cut on each side of the damaged tooth model is made down to the dental model base that allows removal of the damaged tooth model and attached dowel from the rest of the dental model. After the damaged tooth model is removed, the prosthesis can be fitted and adjusted without the spatial limitations encountered when the damaged tooth model is joined to the full dental model. After the prosthesis is made and attached to the dental model segment, the tapered dowel, dowel pin or pins attached to the dental model segment is guided into the respective premanufactured aperture or apertures, in the dental model base which determines the dental model segment in the dental model. Alignment and visual conformity are then assessed.
Alignment is ascertained by evaluating the registration of the repaired tooth with the dental model of the patient's opposing teeth. This is achieved by connecting the upper and lower dental model with an articulator. In some situations, a disposable articulator such as the Vertex® articulator is preferred. In other situations, a traditional metal articulator is preferred. If the prosthesis is out of alignment or does not visually conform to the rest of the patient's teeth, the dental model segment containing the damaged tooth can be removed, adjusted and returned to the dental model base. This process is repeated until proper alignment and visual conformity are achieved. Thus, the model of the damaged tooth may be repeatedly engaged and disengaged with the dental model base.